US8444775B2 - Manufacturing shape memory alloy tubes by drawing - Google Patents
Manufacturing shape memory alloy tubes by drawing Download PDFInfo
- Publication number
- US8444775B2 US8444775B2 US12/680,945 US68094508A US8444775B2 US 8444775 B2 US8444775 B2 US 8444775B2 US 68094508 A US68094508 A US 68094508A US 8444775 B2 US8444775 B2 US 8444775B2
- Authority
- US
- United States
- Prior art keywords
- tube
- coil
- shape memory
- memory alloy
- oxygen getter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active, expires
Links
- 229910001285 shape-memory alloy Inorganic materials 0.000 title claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 title description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 23
- 239000001301 oxygen Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 22
- 230000003647 oxidation Effects 0.000 claims abstract description 11
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 11
- 229910001000 nickel titanium Inorganic materials 0.000 claims description 26
- HLXZNVUGXRDIFK-UHFFFAOYSA-N nickel titanium Chemical group [Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni] HLXZNVUGXRDIFK-UHFFFAOYSA-N 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 7
- 230000007704 transition Effects 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 238000005549 size reduction Methods 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 230000006378 damage Effects 0.000 abstract description 2
- 239000002344 surface layer Substances 0.000 abstract description 2
- 230000003993 interaction Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 11
- 238000000137 annealing Methods 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 239000000314 lubricant Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000013101 initial test Methods 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 229910000953 kanthal Inorganic materials 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910002060 Fe-Cr-Al alloy Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HZEWFHLRYVTOIW-UHFFFAOYSA-N [Ti].[Ni] Chemical compound [Ti].[Ni] HZEWFHLRYVTOIW-UHFFFAOYSA-N 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005183 environmental health Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000006748 scratching Methods 0.000 description 1
- 230000002393 scratching effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
- B21C1/003—Drawing materials of special alloys so far as the composition of the alloy requires or permits special drawing methods or sequences
Definitions
- the present invention concerns improvements in manufacturing, more especially improvements in manufacturing shape memory alloy (SMA) tubing.
- SMA shape memory alloy
- NiTi nickel-titanium alloy
- NiTi nickel-titanium alloy
- one method is to draw the tubing through a series of conical converging dies, in combination with a series of mandrels inserted in the tube internal diameter (“ID”), in order to achieve decreasing tubing outer and inner diameters.
- the dies are made from a hard material, such as a metal carbide or synthetic or natural diamond.
- the combination of such dies and a oxide free NiTi surface can cause a phenomenon known as “galling”, or surface erosion and scratching, due to the particular affinity of the Ti in the NiTi for the carbon in the metal carbide or diamond dies. In extreme cases, galling can cause destruction of an expensive die and process interruption.
- the Nitinol industry has developed methodology to minimise or overcome the problem of galling.
- This uses oxidation of the surface of the Nitinol to form a surface layer of TiO 2 , of thickness in the range of, usually, 600 to 3000 Angstrom (60 to 300 nanometre), which combined with conventional drawing lubricants, eliminates galling and results in successful diameter reduction and a reasonable die lifetime.
- the oxide may be formed by heat treating in an atmosphere that contains oxygen such as air or a controlled combination of inert gas with ppm levels of oxygen in the range of 50-1000 ppm.
- the rapid strain hardening rate and commensurate decrease in ductility of NiTi requires frequent annealing during the tube manufacturing process.
- the annealing and surface oxidation treatments be accomplished simultaneously.
- the rate of oxidation may be so rapid that an excessive surface oxide forms. Therefore a controlled oxygen level created by blending ppm levels of oxygen with inert gases is preferred. In this manner, temperatures required for annealing may be attained without excessive oxidation.
- the very rapid strain hardening rate and commensurate decrease in ductility of Nitinol does not readily permit the formation of seamless tube by the deep draw method.
- the preferred method is to drill a central hole in a centerless ground rod to produce the desired wall thickness or OD/ID ratio (outside diameter/internal diameter).
- the centerless ground OD and drilled/honed ID provide optimum surface conditions for initiating the tube drawing process.
- the material suitable for ID mandrels does not require the same extremely high carbon contents as do die materials nor do they experience the same degree of friction force against the NiTi tube material during the drawing process. Accordingly, the initial tubing does not actually require the formation of an internal oxide layer to prevent galling.
- the present invention provides a method for the size reduction by drawing, of an SMA tube, especially of Nitinol, comprising the protection of the tube from galling caused by a die by forming a OD surface oxide layer, wherein the tube inner surface is protected from oxidation during the heating used to produce the desired OD oxide, which conveniently simultaneously anneals the tube material, using sacrificial or reusable oxygen getters.
- FIG. 1 shows a comparative example of a Nitinol tube heat treated in a conventional manner
- FIG. 2 shows an embodiment according to the invention with the outer diameter having an oxide layer and the inner diameter is protected with mesh plugs as oxygen getter means;
- FIG. 3 shows another embodiment according to the invention with a stretched coil in the tube and acting as the oxygen getter means
- FIG. 4 shows the embodiment according to FIG. 3 where the coil tightly fills the tube.
- the present invention is carried out by inserting a plug of readily oxidisable material at each end of the tube, and located therein.
- the plug should preferably be porous so that the atmosphere used during heat treatment may pass through, whilst at the same time being depleted in oxygen.
- a suitable porous plug may be constructed as a woven sheet of oxygen getter material which is then formed into the plug. The resulting high surface area plug has been found to be highly effective.
- Other porous getter plugs may be formed from compacted powdered getters.
- a coil of getter wire extending throughout the length of the Nitinol tube.
- a coil may be formed from getter wire, having an external coil diameter somewhat smaller than the ID of the Nitinol tube, for example approx 0.001 inch (0.0254 mm) smaller in diameter than the tube, and a coil length slightly longer than that of the Nitinol tube.
- the coil can be readily inserted into the tube by stretching it and then releasing it, allowing it to recover to its original coiled position within the tube. Initial tests have demonstrated that the high surface area coil is so effective that the method of the invention works even while heat treating the tube in air.
- a variant of the above coil spring embodiment is to use a Nitinol wire coil, where the Nitinol alloy has a transformation temperature above room temperature, say 50° C. or above.
- the coil can then be stretched into a shape convenient for insertion into the tube, inserted into the tube, then the coil is heated above the transition temperature and wire heated above the transition temperature, causing the coil to return to its original shape within the tube.
- This offers a high surface area coil with substantially equal oxidation characteristics to the tube ID.
- the Nitinol coil can be stretched once more and removed. Such a coil may be reused after acid-etching oxide layer from its surface to restore its oxygen getter ability.
- Suitable oxygen getter materials for use in the present invention are certain ferrous alloys such as the Fe—Cr—Al alloy “Kanthal” and/or titanium/titanium alloys, providing that the getter material has a high affinity for oxygen, does not provide a source of contamination, has a melting point greater than the annealing temperature and does not bind to the inner surface of the tube during the heat treatment/annealing. Many other getter materials may be suggested by the skilled person.
- the present invention has been shown to operate well in a number of initial tests.
- the present invention potentially offers benefits in combination with the method of manufacturing Nitinol tubes described in U.S. Pat. Nos. 5,709,021 and 6,799,357 which use a soft removable core manufactured from a shape memory alloy.
- the initial stages of manufacture follow conventional tube over mandrel procedures down to the point of inserting the soft martensitic alloy mandrel cores.
- Use of the current invention technology will result in clean smooth ID surfaces that will readily accept the martensitic core mandrels and be subsequently readily removed at final tube sizes.
- the tube IDs are cleaned and/or etched to remove contaminants such as oil, particulate and oxide debris.
- the cleaning is time-consuming, and therefore costly, and it is difficult to inspect the tubes non-destructively to ensure thorough cleaning.
- the present invention offers improved ID surface conditions and cleanliness prior to insertion of the soft core. This may avoid ID surface abnormalities caused by debris being trapped between tube ID and soft mandrel during further drawing and size reduction.
- the present invention reduces or eliminates the need to use highly acid etchants, with consequential savings in material and processing costs, and reducing potential environmental health problems or dangers.
- the avoidance of acid etching itself reduces surface defects caused by the acid etchant.
- the improved ID surface quality also reduces friction between Nitinol tube ID and mandrel OD, which can offer an increase in product tube length during drawing.
- a Nitinol tube was heat treated in the conventional manner, such that an oxide layer forms on both the tube OD and ID. Sectioning the tube shows no difference between the ID surface and OD surface, as shown in FIG. 1 .
- FIG. 2 shows that the tube ID remains bright, with no oxide formation, whereas the tube OD carries an oxide layer.
- a Nitinol coil was stretched at room temperature, below its transition temperature, and pulled through a Nitinol tube.
- the stretched coil is shown clearly in FIG. 3 . Heating the coil and tube above the transition temperature of the coil, results in the coil reforming and tightly filling the tube. This is well illustrated in FIG. 4 .
- the coil provides a very large surface area, which is a particularly effective oxygen getter, and protects the tube ID from oxidation, even if heat treatment is carried out in air.
- the protected tubes prepared according to the invention have been successfully size reduced using a carbide die for the OD and a soft mandrel together with conventional lubricant for the ID.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Extraction Processes (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Glass Compositions (AREA)
- Window Of Vehicle (AREA)
Abstract
Description
Claims (8)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB0719115.8A GB0719115D0 (en) | 2007-10-01 | 2007-10-01 | Improvements in manufacturing |
GB0719115.8 | 2007-10-01 | ||
PCT/GB2008/050871 WO2009044186A1 (en) | 2007-10-01 | 2008-09-26 | Improvements in manufacturing shape memory alloy tubes by drawing |
Publications (2)
Publication Number | Publication Date |
---|---|
US20100282370A1 US20100282370A1 (en) | 2010-11-11 |
US8444775B2 true US8444775B2 (en) | 2013-05-21 |
Family
ID=38701956
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/680,945 Active 2029-11-28 US8444775B2 (en) | 2007-10-01 | 2008-09-26 | Manufacturing shape memory alloy tubes by drawing |
Country Status (8)
Country | Link |
---|---|
US (1) | US8444775B2 (en) |
EP (1) | EP2195128B1 (en) |
JP (1) | JP5335798B2 (en) |
AT (1) | ATE507014T1 (en) |
DE (1) | DE602008006573D1 (en) |
DK (1) | DK2195128T3 (en) |
GB (1) | GB0719115D0 (en) |
WO (1) | WO2009044186A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9192973B1 (en) | 2013-03-13 | 2015-11-24 | Meier Tool & Engineering, Inc. | Drawing process for titanium |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0237912A (en) | 1988-07-28 | 1990-02-07 | Toho Tec Kk | Method of drawing titanium and titanium base alloy pipe |
JPH0679340A (en) | 1992-05-26 | 1994-03-22 | Tokin Corp | Shape memory alloy pipe and its production |
JPH08112614A (en) | 1994-10-14 | 1996-05-07 | Nippon Tungsten Co Ltd | Method for thinning wire of niti series alloy |
US5709021A (en) | 1994-05-11 | 1998-01-20 | Memry Corp. | Process for the manufacture of metal tubes |
JPH1017963A (en) | 1996-06-28 | 1998-01-20 | Tokin Corp | Shape memory alloy tube and its production |
JPH10137835A (en) | 1996-10-31 | 1998-05-26 | Tokin Corp | Manufacture of shape memory alloy tube |
JP2001096307A (en) | 1999-09-28 | 2001-04-10 | Tokin Corp | Method for manufacturing shape memory alloy tube |
JP2001183239A (en) | 1999-12-27 | 2001-07-06 | Kawaso Denki Kogyo Kk | Continuous temperature measuring device |
JP2001187984A (en) | 1999-12-28 | 2001-07-10 | Tokin Corp | Shape memory alloy tube |
JP2001283847A (en) | 2000-03-29 | 2001-10-12 | Mitsubishi Electric Corp | Manufacturing method of positive active material and positive active material as well as lithium secondary battery using same |
WO2003024639A1 (en) | 2001-09-20 | 2003-03-27 | Memry Corporation | Manufacture of metal tubes |
JP2004344950A (en) | 2003-05-23 | 2004-12-09 | Nec Tokin Corp | Method for manufacturing shape memory alloy tube |
-
2007
- 2007-10-01 GB GBGB0719115.8A patent/GB0719115D0/en not_active Ceased
-
2008
- 2008-09-26 DE DE602008006573T patent/DE602008006573D1/en active Active
- 2008-09-26 EP EP08806687A patent/EP2195128B1/en not_active Not-in-force
- 2008-09-26 DK DK08806687.3T patent/DK2195128T3/en active
- 2008-09-26 JP JP2010527543A patent/JP5335798B2/en not_active Expired - Fee Related
- 2008-09-26 US US12/680,945 patent/US8444775B2/en active Active
- 2008-09-26 WO PCT/GB2008/050871 patent/WO2009044186A1/en active Application Filing
- 2008-09-26 AT AT08806687T patent/ATE507014T1/en not_active IP Right Cessation
Patent Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0237912A (en) | 1988-07-28 | 1990-02-07 | Toho Tec Kk | Method of drawing titanium and titanium base alloy pipe |
JPH0679340A (en) | 1992-05-26 | 1994-03-22 | Tokin Corp | Shape memory alloy pipe and its production |
US5709021A (en) | 1994-05-11 | 1998-01-20 | Memry Corp. | Process for the manufacture of metal tubes |
JPH08112614A (en) | 1994-10-14 | 1996-05-07 | Nippon Tungsten Co Ltd | Method for thinning wire of niti series alloy |
JPH1017963A (en) | 1996-06-28 | 1998-01-20 | Tokin Corp | Shape memory alloy tube and its production |
JPH10137835A (en) | 1996-10-31 | 1998-05-26 | Tokin Corp | Manufacture of shape memory alloy tube |
JP2001096307A (en) | 1999-09-28 | 2001-04-10 | Tokin Corp | Method for manufacturing shape memory alloy tube |
JP2001183239A (en) | 1999-12-27 | 2001-07-06 | Kawaso Denki Kogyo Kk | Continuous temperature measuring device |
JP2001187984A (en) | 1999-12-28 | 2001-07-10 | Tokin Corp | Shape memory alloy tube |
JP2001283847A (en) | 2000-03-29 | 2001-10-12 | Mitsubishi Electric Corp | Manufacturing method of positive active material and positive active material as well as lithium secondary battery using same |
WO2003024639A1 (en) | 2001-09-20 | 2003-03-27 | Memry Corporation | Manufacture of metal tubes |
US6799357B2 (en) | 2001-09-20 | 2004-10-05 | Memry Corporation | Manufacture of metal tubes |
JP2004344950A (en) | 2003-05-23 | 2004-12-09 | Nec Tokin Corp | Method for manufacturing shape memory alloy tube |
Also Published As
Publication number | Publication date |
---|---|
DK2195128T3 (en) | 2011-06-20 |
JP2011501699A (en) | 2011-01-13 |
EP2195128A1 (en) | 2010-06-16 |
EP2195128B1 (en) | 2011-04-27 |
JP5335798B2 (en) | 2013-11-06 |
US20100282370A1 (en) | 2010-11-11 |
DE602008006573D1 (en) | 2011-06-09 |
ATE507014T1 (en) | 2011-05-15 |
WO2009044186A1 (en) | 2009-04-09 |
GB0719115D0 (en) | 2007-11-07 |
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